Before slathering sunscreen, know how to use it safely

If you\'re headed to the beach, consider putting up an umbrella and wearing a hat. (AP)

WASHINGTON – The Memorial Day weekend is supposed to be sunny and warm, which will have many digging out their sunscreen from last year. Knowing how to use it correctly is important to avoid a nasty burn.

Most sunscreens have a three-year shelf life, according to the Mayo Clinic, but it will go bad faster if it’s left in the heat.

Since most sunburns are due to ultraviolet b, or UVB rays, dermatologists recommend buying a broad-spectrum sunscreen with SPF 30 or higher. Dr. Lawrence Green with Shady Grove Adventist Hospital in Rockville, Md., suggests keeping clothes on when you’re out of the water.

“Clothing is going to block most of the sun’s rays and you don’t have to worry about applying sunscreen while you’re outside,” Green says. He suggests swim shirts for kids as they keep them cool out of the water and warm in the water while offering protecting from the sun.

Dr. Green recommends reapplying sunscreen every 80 minutes, but he cautions those of us who use the spray-on sunscreens.

“Those worry me a bit. They do make life very easy. You have to be very careful. Spray it close to the child’s body, then rub in after you apply it,” Green says. “Otherwise, what’s going to happen is you have uneven protection from the spray. So take a minute and rub it in and you have even protection throughout the day.”

Consumer Reports rates the top 18 selling sunscreens from SPF 30 to 75 plus on its website. To judge each product, researchers tested the product’s feel on people’s skin and its UVB radiation protection before and after swimming in fresh water.

Also, Consumer Reports researchers ran the new “critical wavelength” test required by the FDA on each sunscreen product to see if they lived up to their broad- spectrum UVA and UVB protection labels.